Case #3 Daily CSI Can you solve it? Snack Shack

Harborville's Beach Snack Shop had been open only an hour when Max stopped in and noticed a new poster announcing a price increase. "I put the sign up this morning," Mr. Levine told him. "I had to raise my prices 10% because I have so many new expenses. Like now I need a new window for my back room. Somebody broke it, trying to get into my store last night." "Have you called the police?" Max asked. Mr. Levine replied, "No. Nothing was stolen." He led Max to a small storeroom in the back and said, “I use this space as an office. Sat here and made my price change poster last night. Soon as I was done, I left it on that old desk. I locked the door to the main part of my store when I left, so whoever got in was stuck in this little storeroom. There’s nothing here to steal." Source: http://kids.mysterynet.com/quicksolve/

How did Max figure it out? When Max left he wandered down to the break wall, where Nathan and Trevor were fishing. "Did you hear that somebody broke a window at the Shack?" he asked. "Nope," Nathan said. "We've been here since dawn and haven't talked to anybody." Trevor gestured to the bucket. "We've caught some big ones." Nathan stood. "But now I'm starving. I've got a dollar left from my allowance. If Mr. Levine is there now, I'm going up to the Shack to get a Big Beach Bun." "Better get another dime from somewhere," Trevor told him. "A dollar's not enough any more. As for me, I'm going home to get a couple sandwiches for myself." "You both stay right here," Max said. "I know which one of you broke that window. You'd better think of a way to pay for it, because I'm telling Mr. Levine." How did Max figure it out?